In inverter devices, uninterrupted power supply devices, machine tools, and industrial robots, semiconductor devices (semiconductor packages), which are independent from the main device and carries a power semiconductor elements, are used.
For example, FIG. 16 is a principal view of a semiconductor deviance carrying a power semiconductor element.
As shown in the figure, in a semiconductor device 100, a parallel connection circuit is provided between a metal bar 130a and a metal bar 130b by bringing main electrodes of an IGBT (Insulated Gate Bipolar Transistor) element 110Na and electrodes of a diode 110Nb into contact respectively with the bars, a parallel connection circuit is provided between the metal bar 130b and a metal bar 130c by bringing main electrodes of an IGBT element 110Pa and electrodes of a diode 110Pb into contact respectively with the bars, the parallel connection circuits are connected respectively in series via the metal bar 130b and sealed with a resin, and the IGBT elements, diodes, and metal bars are electrically connected by a shrinkage pressure of a sealing resin 150 (see, for example, Patent Document 1).
In the semiconductor device 100 having such a configuration, heat generated from the IGBT element 110Na and the diode 110Nb is easily conducted to a heat-dissipating fin 170N. Heat generated from the IGBT element 110Pa and the diode 110Pb is easily conducted to a heat-dissipating fin 170P. The semiconductor device 100 thus has a structure in which heat is conducted to one surface side of each heat-generating semiconductor element, and heat dissipation is facilitated.
Further, it has also been suggested to attempt heat dissipation from both the upper and lower surface sides of semiconductor elements (see, for example, Patent Documents 2 and 3).
A technique has also been known by which a semiconductor element is thermally connected to a cooling body via a thermal compound, a resin sheet, or an insulating layer formed by an aerosol deposition method (see, for example, Patent Document 4).    Patent Document 1: Japanese Patent Application Laid-open No. 2006-134990    Patent Document 2: Japanese Patent Application Laid-open No. 2004-22844    Patent Document 3: Japanese Patent Application Laid-open No. 2007-173680    Patent Document 4: Japanese Patent Application Laid-open No. 2006-165498
However, with some configurations of the conventional semiconductor devices, heat dissipation ability is insufficient and device reliability is reduced, or the increase in heat dissipation ability prevents the devices from being reduced in thickness and miniaturized.